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ND-71762 (E) CHAPTER 2
Page 17
Issue 2
GENERAL INFORMATION FOR CCIS
5.2.2 Sub-Source Office
The Sub-Source Office extracts carrier clocks (24DTI: 1.544 MHz/30DTI: 2.048 MHz) from the DTI opposing to
the Source Office and supplies them to the PLO/OSC (High Precision Oscillator) in the user office.
In preparation for complete clock down from the Source Office, the Sub-Source Office is provided with external
oscillators (EXT. OSC) for backup. Figure 2-12 shows the routes for carrier clock extraction and for backup clocks.
Figure 2-12 Clock Extraction and Backup Routes
External
OSC 0
ACT
Change
CLOCK
Synchronization
Two systems each
ACT
8 kHz (FH)
To Switch
System side
PLO 1
(PH-CK17)
/OSC 1
(PA-CK14)
From DTI
For Backup
Clock receiving route
(max. 4 routes)
PLO 0
(PH-CK17)
/OSC 0
(PA-CK14)
32.768 MHz
External
OSC 1
Note: The OSC (PA-CK14) card is used for the 1-IMG system only.
The PLO (PH-CK17) card is used for the 4-IMG system.
This figure shows an example of the clock supply routes when the PLO0 is in ACT side.